[sdiy] VTL vs. H11F (was: Which is better as a VC resistor?FETor BJT?)

[Justin Owen]

-----Original Message-----
From: David G Dixon [dixon at mail.ubc.ca]
Received: 02.07.2011 17:48:49
To: 'Paul Perry'; synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] VTL vs. H11F (was: Which is better as a VC resistor?FETor BJT?)

>>> You could build one with BJTs too. See Korg MS-10/MS-20.
 
>> Yes.. but you wouldn't WANT  to, because (if you are 
>> referring to the VCA) you need 'selected' transistors, and 
>> also I think that is where the noise comes from. It's a very 
>> ingenious VCA, but.... it isn't what one wants, really.

> Well, the noisy VCA is what gives the MS-20 it's distinctive warm sound,
> IMHO (after playing with a friend's original, mostly for the purpose of
> comparing its filters with mine).  So, perhaps it is what you want if you're
> going after that sound.  However, there are so many superior chips available
> for making virtually noise-free VCAs that I'm not sure why we're bothering
> with this.

I don't want to hijack a thread here but can anyone comment on the selection criteria for the transistor in the Korg VCA?

I used to think it might be 'matched' against something - but I could never find the transistor it was being matched to, then I thought it might be down to the Beta value - but I've recently had someone tell me they couldn't prove this to be the case vs. any other equivalent npn small signal transistor...

Thoughts?

Justin